1. Field of Invention
The present invention relates to purification of water. More particularly, it relates to a device and method for purification of water which has been severely contaminated with particulate and other contaminants such as water from sewage treatment plants, slaughterhouses, foundries, coal pits, and similar venues which traditionally deal with water that is highly contaminated. The device and method herein disclosed features a mechanism for the purification of water of high turbid entering the system, and a unique method of purification of such a high turbidity stream.
Using a combination of mixing of coagulants with the high turbidity fluid stream entering the device, along with a slow circulating fluid stream inside of a unique vessel designed to react to the slowly circulating coagulated fluid stream, the device is capable of a high degree of purification of even the most contaminated water.
2. Prior Art
Highly contaminated water is a byproduct of industrialized societies. Whether it be the sewage created from the mixing of human on other waste products in a sewage collection system from home drains and toilets, or, water contaminated from blood and carcases at slaughterhouse, or, other water contaminated by some other manufacturing plant, processing wastewater of high turbidity, back to a purified form, is a constant and vexing problem for government and industry. The sewage and effluent so created is frequently so contaminated that it is harmful to the environment and to the health of just about any living thing encountering the high turbidity fluid stream.
Ever increasing government standards for discharge water from sewer plants, factories, and manufacturing facilities, is increasing the strain on current systems and methods for purification of high turbidity water streams. This is especially true in the United States and other highly industrialized countries where environmental concerns have caused ever tightening standards for the cleansing of the high volumes of severely polluted water generated in such economies. As developing nations mature, the problem will only increase.
A popular conventional method of dealing with sewage, involves in some cases, sludge ponds where a slurry of water and contaminants piped thereto are cleaned using evaporation and enzymes which concentrate the particulate and other contaminants into ever more dense sewer sludge. The water is separated from the sludge and filtered and generally discharged into the ocean or some other water body. This method is both highly inefficient because of the large amounts of land involved in sludge ponds, and costly due to the extended time required of the sludge to age in the ponds. This method alas also yields water that is still somewhat contaminated. Further still, the method is not a popular manner to handle such wastewater with surrounding residents due to the propensity of the sludge ponds to propagate offending odors, especially in the summer months. To the unfortunate neighbor downwind, such a method of handling sewage waste can be an olfactory nightmare.
Most such conventional wastewater purifiers can only handle wastewater with suspended solids with a turbidity of less than 500 mg/l. When processing wastewater these conventional purifiers have low purifying rates which yield long processing times, and, they consist of large and very expensive mechanical structures. These conventional devices and processes work primarily with the principal of gravity sedimentation or the use of filters. As a general rule, water treated in this manner is still disposed of as it is considered non consumable by man or animal.
Many municipal and industrial wastewater facilities consistently encounter wastewater with turbidity over the 500 mg/l and even up to 5000 mg/l. Because of ever this ever increasing flow of dirtier sewage and other high turbidity wastewater streams, and stagnant or diminishing municipal and industrial facilities to process increasing flows, novel methods and devices have arisen in recent years in attempts to process and clean the ever increasing rivers of sewer water and other water of high turbidity. Such methods include the use of live shrimp in sludge ponds to devour the contaminants and speed the fluid flow, to the use of reverse osmosis filters to remove contaminants. Unfortunately the water the shrimp are subjected to, sometimes is even too contaminated for them causing their untimely demise. The particulate and other contaminants encountered by reverse osmosis filters in such conditions continually clog the fine membranes used to filter contaminants. Such failures contribute to the high cost of processing high turbidity wastewater streams.
Other mechanisms have also arisen in attempts to more efficiently handle increasing effluent fluid flows. Such mechanisms include machinery using hydrodynamics, paddles, and similar mechanical means to help separate water from particulate and other contaminants therein. Such prior art has attempted to address some of the aforementioned problems and solutions but without great success.
U.S. Pat. No. 5,690,813 (Coale) teaches an apparatus for separating contaminated waste water using a centrifuge. This device uses a high speed fluid flow and the natural action of centrifugal force, to separate heavy solids from water. The particulate is then directed against vanes at the circumference and collected in a sump. However, Coale is a complicated array of baffles possibly subject to clogging and requires a high speed circulation of the slurry to effectively separate particulate from fluid requiring high speed pumps.
U.S. Pat. No. 4,865,751 (Smisson) teaches water purification system using centrifugal force and a series of vanes and fluid energy inlets to circulate and purify water. However Smisson is subject to clogging if circulation is not kept to a high enough velocity, and requires a plurality of inlets for energized fluid to maintain sufficient velocity to overcome clogging.
U.S. Pat. No. 5,698,099 (Fagan) discloses a hydrodynamic separator using centrifugally accelerated sludge through a plurality of filter openings to separate solids from liquid. Fagan requires a relatively high speed fluid stream and the filters would be prone to clogging if the fluid steam slows below a certain point or if the particulate clumps onto the filter.
As such, there exists a need for an easily maintained and operated separator to separate particulate and other solids in solutions from the solution itself. Such a device should require a minimal fluid velocity to achieve the separation and thereby require less energy than high fluid velocity systems. The device should also be resistant to clogging and easily maintained to prevent system shut down from clogging. Such a device with low energy requirements and easy maintenance would therefore work better in industrialized and municipal installations, and, lend itself to installation in countries badly in need of water purification but lacking in energy and technical maintenance skills.
Applicants"" system and device feature an easily maintained and utilized apparatus providing for a high degree of purification of high turbidity water and wastewater. In its best mode it utilizes coagulants mixed with incoming wastewater fluid and thereafter entering a purifying vessel to better concentrate the floating solids into larger particles or flocculent. The slurry of coagulant and suspended solid contaminants and water is then circulated at a slow velocity which is sufficient to overcome the gravitational force on the suspended solids and cause the suspended solids in the slurry to rise to a predefined level in the vessel. By carefully maintaining the speed of the liquid circulation, the suspended solids will never rise above predefined level in the vessel. This mode of the device and method of processing wastewater is capable of handling suspended solids in wastewater higher than 500 mg/l and as high as 5000 mg/l directly and continuously.
During their rise caused by the rotating flow of fluid in the vessel, the suspended solids interact with each other and the coagulant and form larger suspended solids commonly called flocculent. It is therefore desirable that the fluid stream circulate slowly to allow more time for such clumping and enlargement of flocculent. Because the device herein disclosed features a slow rotation rate or upward flow speed of the wastewater in the vessel, more time is allowed for the reaction to take place and for the suspended solids to form larger flocculent.
At a determined point of rise of the slurry, the circulation speed of the fluid within the vessel, which is determined by design, will allow the slurry only to rise upward only to the predefined level in the vessel. A first filtration zone is thereby formed of a layer composed of coagulated contaminant suspended solids which have formed into larger flocculent particles and reached the determined point of height in the vessel. Subsequent suspended particles and flocculent in the wastewater stream reach this first filtration zone where they are intercepted by the layer of flocculent and suspended solids already circulating at the first filtration zone level. The circular motion of the wastewater therein acts to force the ever gathering mass of flocculent and suspended solids in the coagulation zone higher.
This rising action forces flocculent and any smaller particles of suspended solids on the upper layer of the first filtration zone to rise over the lip of a centrally located collector around which the slurry circulates. At this point in the height of the vessel, a defecation zone is formed in the vessel where the collector section terminates at the lip of the collector, and is created when the area available for fluid circulation is immediately increased due to the termination of the collector section. Upward circulating flocculent and smaller suspended solids move toward the lip of the collar and are deposited over the lip and into the collector by the circulating fluid stream.
This flow of substantially all of the flocculent and other suspended solids, into the collector, is the result of a number of natural actions. First, the diameter of the collector around which the fluid slurry circulates reduces the area for circulation of the fluid stream around it. The termination of the collector at the lip increases the area present for the path of the upward circulation of the flocculent and suspended solids slowing the upward speed of both by natural action of increased area thereby forming a first filtration zone. This first filtration zone formed of the flocculent and smaller suspended solids forced up from below the filtration zone by the upward circulation of the liquid is also continually drawn into the collector due to the inability of the slower fluid circulation speed to raise the suspended solids where the collector terminates.
As such, the larger flocculent and other suspended solids are forced to a level just over the edge or lip of the collector where gravity and pressure differences caused by the point eddy motion principal, will draw substantially all of the larger flocculent and smaller suspended solids toward the lower presser in the center of the vessel and into the collector. As a consequence the suspended solids and flocculent that are undesirable in the water, become the filter for their own removal therefrom. Additionally, the lower pressure existing in the collector naturally draws the flocculent and smaller suspended solids toward the lower pressure at the mouth of the collector where they fall into the collector. Thus gravity and lower fluid pressure work in concert to remove the flocculent and suspended solids from the wastewater mix and deposit them into the collector. The result being that only water that is substantially free of contaminants and suspended solids to rise further past the lip of the collector.
Clean water continues past the first filtration zone formed of the flocculent and suspended solids to a secondary filtration zone consisting of buoyant ball-shaped components floating at the secondary filter zone in the vessel. Plastic balls of a specific gravity lighter than water work well for this layer as they naturally float to the high level in the vessel. This layer of ball-shaped components serves two purposes. First, it serves as a secondary filtration zone which tends to remove any small remaining suspended solids that may have inadvertently made it past the natural filtration zone at the first filtration zone. Concurrently, the layer of buoyant ball-shaped components, create a pressure differential between the fluid at the bottom of the filtration zone layer and the water exiting the filtration zone layer at the top of the vessel. This is because fluid such as wastewater first encountering the bottom of the layer of ball-shaped components is at a higher pressure than fluid exiting the top or exit of the layer of ball-shaped components in accordance with the filter hydraulic principal. Thus, fluid pressure is higher at the lower or bottom of the filter zone than it is in the middle of the filter zone or exit side of the secondary filtration zone.
Using this naturally occurring principal of pressure differential, the circulation of fluid through the vessel can be additionally enhanced by the addition of return conduits which communicate between the bottom or lower levels of the return or sludge storage cavity which collects the slurry of coagulated solids from the coagulation zone. The communicating conduit will have a slightly lower fluid pressure at the point of communication of the conduit with the return cavity thereby tending to draw water up into the conduit which will exit into an area substantially at the middle portion of the secondary filter zone which is the source of lower pressure. Lower velocity of the fluid caused thereby is however insufficient to force the coagulated flocculent or suspended solids remaining in the slurry up to the level of the secondary filter zone due to the mass of the coagulated solids being too heavy to be overcome by the slow fluid stream in the sludge storage cavity. As such, increased output is achieved of purified water with the addition of the communicating conduits as is additional concentration of the suspended solids removed from the water.
While the device would function without the return conduits, the efficiency of the device is significantly enhanced by their addition and as such, the best mode of the device would feature one or a plurality of return conduits to condense the solids in the storage cavity by removal of additional water therefrom.
The device herein disclosed, uses a slow circulation of fluid inside the vessel and requires minimal energy to operate. By using the pressure differential and eddy principal to separate coagulated solids from circulating lighter liquid, a high degree of filtration is achieved without the need for vanes or filtering screens which might clog thereby decreasing maintenance requirements. Additional efficiency in both purified fluid collection and sludge condensation is achieved with the addition of fluid return conduits. Because of this high efficiency and low power and maintenance requirements, the device would not only be applicable to current municipal and industrial sewage plants, it would be ideal for use in countries where energy available is minimal and technical personnel to complicated devices are not readily available. It could thus be immediately introduced into the stream of commerce to aid in purification of sewage and also of contaminated water into potable or drinking water in third world countries as well as increasing efficiency in industrialized countries. Because the device uses the contaminant itself as a filter, the device is capable of handling water with suspended solids over 500 mg/l and as much as 5000 mg/l which currently cannot be adequately filtered by conventional equipment and methods. Such ability would allow the device to process water from ceramics plants, paper mills, and printing and dying mills, known for high solid content as well as to pre-treat sea water used to cool nuclear power plants to lower the suspended solid content thereof.
An object of this invention is providing a highly efficient water purification system.
Another object of this invention is to provide a high degree of purification using a relatively slow moving fluid stream thus using minimal energy to accomplish purification.
An additional object of the invention is the provision of a device that uses the contaminant itself as the filter material for the contaminant, thereby reducing costs through elimination of filters, grids, and other structures and material normally required.
A further object of this invention is the provision of highly concentrated sludge thereby compacting disposal problems while concurrently yielding high volumes of purified water from incoming contaminated water.
An Additional object of the invention is to provide a device which yields highly purified water from water contaminated by sewage or other contaminants, but has a minimum of maintenance required which can be handled by low skilled personnel.
Another object of this invention is to provide a device for the pre-treatment of seawater used to cool nuclear power plants or later used for reverse osmosis treatment.
Further objects of the invention will be brought out in the following part of the specification, wherein detailed description is for the purpose of fully disclosing the invention without placing limitations thereon.